The field of the invention relates to assemblies for slitting relatively wide coils of material, preferably metal, into relatively narrow strips.
Slitting assemblies have been used to transform wide coils of material, usually metal, into relatively narrow strips. A known system has included a number of different components which cooperate to provide the desired product. A roll of wide stock material is positioned on a fixed or positionable payoff. The payoff may be positioned, either manually or automatically, so that it lines up with a slitter. A Ruesch Model 247 Payoff as produced by the H. J. Ruesch Machine Company of Springfield, N.J. is an example of a payoff which has been successfully employed.
The strip of metal which unwinds from the payoff passes through the rollers of a pulling payoff bridle and into an entry looping pit so that no tension exists between bridle and payoff. It then enters the slitter where it is cut into relatively narrow strips. The driven Ruesch Model 146 slitter is an example of a slitter which is suitable for warehouse duty, and can handle coils up to 48 inches wide with a thickness of 0.125".
An exit looping pit is provided after the slitter such that the narrow strips are not subject to tension between the slitter and a tension stand located after the exit pit. The tension stand tensions the strips before rewinding.
The strips proceed from the tension stand to a rewinder where they may be either traverse (zigzag or oscillated) or pancake wound. The former procedure provides a coil which is several strip widths wide, while the latter provides a coil having a width of only one strip. Traverse winding is often preferred as many more feet of strip material can be included in a roll of given diameter.
The rewinder may be provided with a hydraulic or pneumatic coil stripper to push the finished slit coils off the arbor to a turnstile or other coil receiver. Ruesch Model Numbers 247-N-2551-5882 and 247-N2572-5918 are examples of such rewinders.
Other prior art assemblies have tensioned the strips all the way from the slitter to the rewinder. However, better slitting is accomplished if the metal proceeding through the slitter is not under tension. This is particularly true for thin gauge materials.
A problem which has arisen in previous constructions occurs where the original unslit coil does not have a uniform thickness. The strips which are manufactured from the coil will therefore have varying thickness. When the strips are wound on the rewinder, one or more of the coils of thicker material will have a larger diameter than the others for a given footage of strip material. The coils which become larger in diameter cause the material to wind at a faster speed than others as the rotational velocity for all the coils is the same. As a result some of the strands of thicker material will be tightly wound and strands of thinner material will be loosely wound.